Tune compiler tracing usage of 'frame's. (iree-org#15216)

Compiler tracing was a bit confusing when profiling to find
iree-org#15209.

First, this fixes an issue where frame frames were unbalanced upon
recursing into the compiler, leading to confusing rendering in the Tracy
UI that could misattribute sections of the compiler running to the
"GlobalOptimization" pass pipeline:

![image](https://github.com/openxla/iree/assets/4010439/9407b54d-4e5f-4ed1-9232-4f870561ac48)

Second, this tweaks how frames are defined for unnamed pipelines and
adds a scope for bytecode translation (which happens outside of a pass
pipeline):

![image](https://github.com/openxla/iree/assets/4010439/43cc02ba-e9e6-4a49-8ebe-972be2ca7106)

compiler/src/iree/compiler/API/Internal/CompilerDriver.cpp

@@ -908,6 +908,8 @@ bool Invocation::runPipeline(enum iree_compiler_pipeline_t pipeline) {
   if (failed(passManager->run(parsedModule))) {
     return false;
   }
+  // Done with the pipeline, mark the start of a new 'frame'.
+  IREE_TRACE_FRAME_MARK();
   return true;
 }
 

compiler/src/iree/compiler/Dialect/VM/Target/Bytecode/BytecodeModuleTarget.cpp

@@ -566,6 +566,7 @@ translateModuleToBytecode(IREE::VM::ModuleOp moduleOp,
                           IREE::VM::TargetOptions vmOptions,
                           IREE::VM::BytecodeTargetOptions bytecodeOptions,
                           llvm::raw_ostream &output) {
+  IREE_TRACE_SCOPE();
   moduleOp.getContext()->getOrLoadDialect<IREE::Util::UtilDialect>();
 
   if (failed(canonicalizeModule(bytecodeOptions, moduleOp))) {

compiler/src/iree/compiler/Pipelines/Pipelines.cpp

@@ -159,19 +159,36 @@ void buildIREEPrecompileTransformPassPipeline(
     break;
   default:
     if (compileFrom < IREEVMPipelinePhase::Preprocessing) { // late-entry.
-      IREE_TRACE_ADD_BEGIN_FRAME_PASS(passManager, "Preprocessing");
+      // Not a large enough phase for IREE_TRACE_ADD_[BEGIN,END]_FRAME_PASS.
       IREE::buildPreprocessingPassPipeline(passManager, preprocessingOptions,
                                            hooks.pipelineExtensions);
-      IREE_TRACE_ADD_END_FRAME_PASS(passManager, "Preprocessing");
     }
     if (compileTo == IREEVMPipelinePhase::Preprocessing)
       return; // early-exit
 
     if (compileFrom < IREEVMPipelinePhase::GlobalOptimization) { // late-entry
-      IREE_TRACE_ADD_BEGIN_FRAME_PASS(passManager, "GlobalOptimization");
+      // This pass pipeline recursively invokes the compiler if constEval is
+      // enabled. In that case, we have to be careful to not emit unbalanced
+      // trace frames:
+      //   begin 'GlobalOptimization'
+      //   begin 'Input'
+      //   end   'Input'
+      //   begin 'GlobalOptimization' <-- unbalanced! Use a different name.
+      //   end   'GlobalOptimization'
+      //   ...
+      //   end   'GlobalOptimization'
+      if (globalOptimizationOptions.constEval) {
+        IREE_TRACE_ADD_BEGIN_FRAME_PASS(passManager, "GlobalOptimizationConst");
+      } else {
+        IREE_TRACE_ADD_BEGIN_FRAME_PASS(passManager, "GlobalOptimization");
+      }
       GlobalOptimization::buildGlobalOptimizationPassPipeline(
           passManager, globalTransformOptions);
-      IREE_TRACE_ADD_END_FRAME_PASS(passManager, "GlobalOptimization");
+      if (globalOptimizationOptions.constEval) {
+        IREE_TRACE_ADD_END_FRAME_PASS(passManager, "GlobalOptimizationConst");
+      } else {
+        IREE_TRACE_ADD_END_FRAME_PASS(passManager, "GlobalOptimization");
+      }
     }
     if (compileTo == IREEVMPipelinePhase::GlobalOptimization)
       return; // early-exit

compiler/src/iree/compiler/Utils/TracingUtils.cpp

@@ -70,10 +70,8 @@ class TraceFrameMarkBeginPass
   TraceFrameMarkBeginPass(llvm::StringRef name) { this->name = name; }
 
   void runOnOperation() override {
-    // Always mark the top level (unnamed) frame.
-    IREE_TRACE_FRAME_MARK();
-
     if (!name.empty()) {
+      IREE_TRACE_FRAME_MARK(); // Top level (unnamed) frame.
       IREE_TRACE_FRAME_MARK_BEGIN_NAMED(name.data());
     }
   }